Crews have contained a brush fire burning near Highway 4 in Contra Costa County that prompted lane closures Sunday afternoon.

The fire charred at least 50 acres.

CHP officials had to stop traffic on eastbound Highway 4 near Franklin Canyon Road because of downed power lines. It's unclear at this time, whether the power lines caused the fire or if the wires came down because of the fire.

Crews used heavy equipment to build a containment line.

Firefighters said structures were threatened. It is a rural area, so there are horses, other animals, barns and outbuilding's nearby.